Fibromyalgia patients may take low doses of antidepressants to relieve chronic pain and improve sleep. Because the ability to tolerate side effects could be a key to the success of an antidepressant treatment, researchers explored drug-specific adverse effects and individual tolerability to antidepressants.

“Understanding adverse effects and their impact on patients’ quality of life is crucial in modern clinical medicine and poses a substantial challenge to clinicians who face a exponentially growing range of available medical therapies,” Timo Siepmann, the principal investigator of the study, said in a press release.

The team performed a meta analysis of the reported adverse effects of commonly used antidepressants. The study included the tricyclic antidepressants (TCAs), such as Pamelor (nortriptyline) and Elavil (amitriptyline), and serotonin reuptake inhibitors (SSRIs), such as Effexor (venlafaxine), Prozac (fluoxetine), Savella (milnacipran) and Cymbalta (duloxetine).

Researchers found that almost all antidepressants presented significant side effects, which ranged from dizziness, dry mouth, and drowsiness to palpitations, weight gain, sexual and urinary dysfunction, and hypertension.

In addition, researchers also took into account whether treatment was discontinued due to the severity of these side effects.

They realized that some patients may tolerate certain side effects better than other patients. For instance, some sedation might be tolerated, and perhaps even be desirable, in a chronic pain patient with sleep disruptions or insomnia. In contrast, dizziness and drowsiness are not desirable side effects in individuals who drive vehicles or operate heavy machinery.

In the case of fibromyalgia patients, their symptoms of fatigue and decreased energy might be aggravated by drowsiness, a TCAs common side effect. In this case, SSRIs — also approved by the FDA for treatment of fibromyalgia — may be a better option.

Overall, these results may help physicians to personalize antidepressant treatment for chronic pain patients.

Siepmann concluded by stating that “further research is needed to improve general treatment recommendations and enable personalized multimodal therapy which is tailored to the patient’s individual health situation and includes non-pharmacological strategies in addition to pharmacotherapy.”